Many types of vehicles and machines require flexible hose and/or electric line systems for conducting pressurized fluids and/or electric current to moving components. For example, in industrial lift trucks it is often necessary to provide several flexible hydraulic hoses and electric cables so as to provide both hydraulic and electrical power to the elevatable carriage on the upright for the purpose of operating and controlling one of various material handling devices or attachments which may be mounted on the carriage.
In an exemplary lift truck application hydraulic hoses are reeved between and within the extensible sections of the upright, generally paralleling the lift chains. Reels or sheaves are normally mounted on the upright to guide the hoses and cables, and springs are used to hold them taut. Such systems are usually limited to a pair of hoses, sufficient for simple attachments mounted on the carriage, but inadequate for more complex attachments.
In other lift truck arrangements hydraulic hose reels are mounted on the outside of the upright, which may be in addition to the above internal system when more than two hoses are required. Such hose reels are relatively large, bulky and expensive, and being mounted externally are subject to damage. Being mechanical they are, of course, subject to wear, and required hose reel swivel seals are a source of hydraulic leaks. Hoses sometimes stack up in the reel and bind or run off the reel. Inherent in such systems is an undesirable pressure drop between the pump and the attachment because of the required number of hydraulic fittings which are used.
In some prior applications it has been possible to eliminate such reels and sheaves by utilizing troughs connected to relatively fixed and moving elements of any machinery in which the moving element moves in oscillatory straight-line motion and flexible hose or electric cable is connected to the far ends of the fixed and movable elements so that the hose or cable rolls from one trough to the other without the need of a guide reel.
Electric cable reels are used to provide electrical communication with various devices in many applications in which a moving device is connected by extensible cable, such as in the lift truck application discussed above. Such reels and cable are subject to physical damage, in addition to cable pile-up, jamming and run-off. Such reels are relatively expensive, large and bulky when more than a few electric lines are involved.
Certain prior patents illustrate two or more hoses bonded together in a hose manifold or assembly for conducting one or more fluids, and the like, from one location to another. Exemplary are U.S. Pat. Nos. 2,916,055 and 3,907,022. The basic lack in all known prior art is the absence of the concept of an arcuate configuration in cross-section from which flow the advantages of this invention.
The principle which governs the kinematics of my invention can be demonstrated by a steel measuring tape of the type which has a concave side and a convex side; i.e., the cross-section of the tape has an arcuate shape. The tape when bent back upon itself exhibits the properties of interest here, viz., that of remaining relatively stiff and straight along the trailing lengths of the tape on opposite sides of the loop, the bend of the loop inherently being of uniform radius. The tape then has the characteristic of being able to roll in either direction while the loop of uniform radius is maintained as one straight section is pushed toward or pulled away from the loop.